I would just like to say sorry for some of the comments and assumptions made against yourself.
I cannot seem to find in your post these assumptions that had everyone else so up in arms and truthfully quite aggressive and rude about.
I cannot seem to find in your post where you were you going to abuse your dogs by only breeding for sheer profit. Rather to me it sounded as though you had very much been taken with your chosen breed and were seriously considering becoming a breeder hence being here asking questions and seeking advice.
I have no experience when it comes to the Westies so am little help to you I'm afraid. But with the desexed female you already have,there could be many variables so it's hard to pin it down and actually give an expectation when in reality things could play out so differently
She may show signs of jealousy which would be my first concern though